Gas separating membrane having a polycarbodiimide resin layer

Abstract

Disclosed is a gas separating membrane comprising a layer made of a polycarbodiimide resin having repeating units represented by formula (I): ##STR1## wherein R represents a divalent organic group. The gas separating membrane available according to the present invention has high permeability and separation selectivity as well as excellent permeating performance, and further has excellent heat resistance, chemical resistance and durability.

What is claimed is: 
     
       1. A gas separating membrane comprising a layer composed of a polycarbodiimide resin which has repeating units represented by formula (I): ##STR5## wherein R represents a divalent organic group formed from an organic diamine. 
     
     
       2. The gas separating membrane of claim 1, which is a composite membrane comprising: (1) an active separating layer of a polycarbodiimide resin which has repeating units represented by formula (I): ##STR6## wherein R represents a divalent organic group and (2) a porous substrate layer.   
     
     
       3. The gas separating membrane of claim 2, wherein said porous substrate layer is formed of a polyamide resin, polyimide resin, polyether sulfone resin or polysulfone resin. 
     
     
       4. The gas separating membrane of claim 1, wherein the polycarbodiimide resin has a number-average molecular weight of 3,800 to 100,000. 
     
     
       5. The gas separating membrane of claim 1, wherein the polycarbodiimide resin is one prepared by using a bisurethane as a raw material together with an organic silicon halide, a basic compound and a polymerization catalyst.